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Nutritious breakfast food or heart-clogging killer?

It seems the perennial question about eggs won't be going away any time soon, with a recent study suggesting that regularly eating yolks is almost as bad for your arteries as smoking by accelerating atherosclerosis (the buildup of plaque on artery walls), which is a major factor for strokes and heart attacks.

Researchers at the University of Western Ontario examined more than 1,200 patients at the London Health Sciences Centre's University Hospital, using an ultrasound to measure their plaque buildup. Participants also filled out a lifestyle survey, which included questions about their smoking habits and egg yolk consumption.

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The results, published Monday in the journal Atherosclerosis, showed that plaque buildup increased linearly after the age of 40, but increased exponentially for smokers and egg-yolk eaters. In other words, both smoking and eating yolks can speed up atherosclerosis.

The study also found that people who ate three or more yolks a week had substantially more plaque on their artery walls than those who ate two or less yolks – building up plaque at two-thirds the rate of regular smoking.

"It has been known for a long time that a high cholesterol intake increases the risk of cardiovascular events, and egg yolks have a very high cholesterol content," said David Spence, the lead researcher and a neurology professor at Western, in a press release. "In diabetics, an egg a day increases coronary risk by two to five-fold."

But not everyone agrees. According to a 2011 study from Harvard University, eating one egg day a day does not increase the chance of a heart attack or stroke in healthy men. But the findings did suggest that if you have diabetes, you should avoid eating the yolk.

The debate over the health virtues of eggs has been going on since the 1960s, when fears about cholesterol-heavy foods led to public-health campaigns warning Canadians about the dangers of eating eggs.

Dr. Spence's previous study, released in 2010, made headlines when researchers suggested that one egg yolk is worse, in terms of cholesterol, than KFC's Double Down sandwich – a gluttonous meal consisting of bacon and cheese squeezed between two pieces of fried chicken.

How many eggs do you eat in a week? Will this study make you change your egg consumption habits?

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